Modular power roller conveyor

ABSTRACT

A modular power roller conveyor is described having a conveyor section for transporting a product unit. The conveyor section comprises a number of active zones, each active zone containing means for sensing the entry of a product unit into the active zone. A programmable controller generates activation signals to a drive roller in response to the means for sensing. A plurality of carrier rollers are slaved to the drive roller within the active zone such that activation of the drive roller actuates all of the carrier rollers to drive the product unit through the active zone and into the next active zone. The programmable controller also generates a deactuation signal to deactivate the active zone as a product unit exits the zone.

RELATED APPLICATION

[0001] This application is a division of prior application Ser. No.08/762,314, filed on Dec. 9, 1996, pending, which is a continuation ofprior application Ser. No. 08/331,063, filed Oct. 28, 1994 now U.S. Pat.No. 5,582,286.

TECHNICAL FIELD

[0002] The present invention relates to a conveyor systems and moreparticularly to a modular conveyor system and a method for conveyoroperation.

BACKGROUND OF THE INVENTION

[0003] The movement of large numbers of product units, such as a tray orpallet, around a manufacturing or processing facility has long proved tobe an expensive and time consuming task. Presently, most systems forcarrying out the movement of product units around a manufacturingfacility utilize static systems that are set up to maintain andtransport product units using a particular configuration that is noteasily changed. The problem with these type of systems is thatmanufacturing or processing requirements may change and reconfigurationof the static system is not easily achieved. Thus, weeks or even monthsmay be required to reconfigure a conveyor system to meet the changingneeds of the facility.

[0004] Prior art conveyor systems have many problems relating to themaintenance and complexity of the systems. One problem with existingconveyor systems is that the systems normally have complex mechanicalgearing consisting of a large number of components. This type ofmechanically geared conveyor system requires a great deal of maintenancein order to keep the system in peak operating condition. Air pressureoperated systems require a complex pneumatic system in order to operatethe conveyor. Pneumatic systems require labor intensive maintenanceprocedures in order to achieve peak operating conditions of the system.Existing systems also create a great deal of noise when operating.Mechanically geared systems normally comprise a large number of chainand roller drive assemblies creating mechanical noise during operation.Pneumatic systems necessarily require the use of noisy compressors andair injection procedures which add to the noise pollution of the workenvironment. Finally, each of the above described systems require agreat deal of power to operate since the entire system must function atthe same time, no matter how many or few product units are present uponthe conveyor system at any particular time.

[0005] Therefore, a conveyor system is needed which will allow amanufacturing or processing facility to quickly and easily reconfigurethe system to changing facility needs, provide easy maintenancerequirements, decrease the amount of noise pollution to the workenvironment, and provide lower energy consumption than is possible withpresently existing systems.

SUMMARY OF THE INVENTION

[0006] The present invention overcomes the foregoing and other problemswith a modular power roller conveyor system and onboard PLC/power card.The system consists of modular units having a frame for holding aplurality of carrier and drive rollers. These modular units are easilyconnected to form an adaptable conveyor system. The conveyor section ofeach module is divided into a number of active zones. Each active zonecontains a photosensor and reflector pair for detecting the entry of aproduct unit into the active zone, a drive roller for driving rollerswithin the active zone, and a plurality of carrier rollers actuated inresponse to movement of the drive roller. Each zone is connected to aPLC/power card. Upon detection of a product unit by a photosensor, acontrol unit generates an activation signal to the drive roller of theactive zone the product unit is entering. The drive roller drives thecarrier rollers within the active zone allowing the product unit to betransported through the active zone and into the next active zone. Atthe same time, the controller generates a deactivation signal to thedrive roller of the active zone the product unit is exiting to conservesystem power.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 is a perspective view of one section of the modular powerroller conveyor of the present invention;

[0008]FIG. 2 is a cut-away representation of one side rail and severalrollers of the section of FIG. 1 and the internal connecting brackets;

[0009]FIG. 3 is a side view of one of the carrier rollers;

[0010]FIG. 4 is a lateral cross-section view of the conveyor section ofFIG. 1;

[0011]FIG. 5 is a lateral view of the interface between adjacentsections showing the attachment of the roller shafts to the side rail;

[0012]FIG. 6 is a top view of the straight conveyor section of FIG. 1comprised of four active zone;

[0013]FIG. 7 is a perspective view of a curved conveyor section of themodular power roller conveyor of the present invention;

[0014]FIG. 8 is a tapered roller of the curved conveyor section of FIG.7;

[0015]FIG. 9 is a top view of the curved conveyor section of FIG. 7;

[0016]FIG. 10 is a top-view of a left-hand divert section of the powerroller module;

[0017]FIG. 11 is a lateral view of a left-hand divert section of FIG. 10of the power roller module;

[0018]FIG. 12 is a top view of the divert section of FIG. 10illustrating the divert arm in an unactuated first position inside ahollow side rail;

[0019]FIG. 13 is a lateral view of the divert section of FIG. 12;

[0020]FIG. 14 is a top view of a divert section of FIG. 10 illustratingthe divert arm in an actuated second position extending from the hollowside rail across the conveyor and diverting a product unit from a firstpath to a second path;

[0021]FIG. 15 is a lateral view of a divert section of FIG. 14;

[0022]FIG. 16 is a circuit wiring diagram of the controller; and

[0023]FIG. 17 is a schematic of a logic circuit within the controller.

DETAILED DESCRIPTION

[0024] Referring now to the Drawings, and more particularly to FIG. 1,there is illustrated a perspective view of one embodiment of a module 8for the modular power roller conveyor of the present invention. Themodule 8 is a straight conveyor section 10 for transporting receivedproduct units. The straight conveyor section 10 is supported by legs 11and consists of a left side rail 12, a right side rail 13, a pluralityof carrier rollers 14 and drive rollers 16 mounted between the left siderail 12 and the right side rail 13. The drive rollers and the carrierrollers may be of the type manufactured by Interroll Corporation andidentified as model Driverroll. The carrier rollers 14 and drive rollers16 are interconnected by a plurality of o-ring bands 17 such thatactuation of a drive roller will cause actuation of any carrier rollersconnected thereto.

[0025] The side rails 12 and 13 have a cross-sectional shape thatdefines an interior chamber for placement of a controller (FIG. 16) andcontrol wiring (not shown). Openings 18 within side rails 12 and 13facilitate operation of a plurality of photosensors 34 and reflectors 36(FIG. 4) for sensing the presence of product units on the straightconveyor section 10. Mounted to the side rails 12 and 13 at each end ofthe straight conveyor section 10 are internal connecting brackets 22with holes 45 for bolts and nuts to enable the straight conveyor section10 to be interconnected with another module 8 and form a conveyorsystem. An electrical connector mounted in an opening 23 enables amodule 8 to be electrically connected to other modules or to a powersupply.

[0026] Referring now to FIG. 2, there is shown a cut-away representationof the side rail 13 and several rollers 14 and the internal connectingbracket 22. Holes 45 in the connecting bracket 22 allow structuralconnection with an adjoining module 8, while an opening 23 in theinternal connecting bracket 22 allows wire connection between electroniccomponents of adjacent modules 8. A cover 41 protects the wireway, andis connected to side rail 13 with single-turn screws 35 and rifled holes43. The shafts on which the rollers 14 and 16 turn are spring loaded atone end 28, and the spring loaded end passes through holes in the siderail 13.

[0027] Referring now to FIG. 3 and FIG. 4, there is shown a side view ofone of a carrier roller 14. The carrier roller surface 20 is preferablyfabricated from a galvanized steel tube. The shafts 28 of the carrierroller 14 are spring loaded at each end allowing for easy removal andmounting of the carrier roller within the side rails 12 and 13. Eachcarrier roller 14 also includes a pair of grooved channels 30 forplacement of the o-ring bands 17 (FIG. 1) between adjacent carrierrollers. Each drive roller 16 has an outward appearance similar to thatof the carrier rollers 14. The drive roller 16 has a roller surface 26,spring loaded shaft 28 on one side and a lock nut and a full nut on theopposite side, and groove channels 30. However, the drive rollers 16further include internal gearing and an electric motor. The driverollers 16 are preferably twenty-four volt electric conveyor rollersmanufactured by the Interroll Corporation.

[0028] Referring to FIG. 4, there is shown a lateral cross-section viewof the conveyor section 10 more fully illustrating the placement andoperation of the photosensors 34 and reflectors 36 mounted along theconveyor section 10. The photosensor 34 is mounted to a lower sensorbracket 38. Lower sensor bracket 38 connects to an upper sensor bracket40 which connects to the upper surface of left side rail 12. Theassembly is positioned in such a manner that a beam 42 from photosensor34 is passes through opening 18 within left side rail 12. The beam 42passes laterally across the conveyor section 10 and passes throughopening 18 in the right side rail 13 to strike reflector 36 and isreflected back to sensor 34 where the reflected beam is detected. Thereflector 36 is mounted to the interior of the right side rail 13 by areflector bracket 44.

[0029] Referring to FIG. 5, there is shown a lateral view of theinterface between adjacent modules with the bolts 28 attaching theshafts of rollers 14 to the side rail 13. A connecting bracket 22 isshown connecting adjacent modules 8 by means of bolts 37 and nuts 39.Electrical connection is made by means of connectors (not shown) mountedto openings 23. The cover 41 is attached at several points 35.

[0030] Referring now to FIG. 6, there is illustrated a top view of astraight conveyor section including four active zone areas 50 a-50 d.Each active zone includes a drive roller 16 and plurality of carrierrollers 14 slaved to the drive roller by o-ring bands 17. Also includedwithin each active zone 50 is a photosensor 34 and a reflector 36located prior to the entry end 52 of the active zone. A programmablecontroller 54 (FIG. 16) is mounted in the left side rail 12 and is incommunication with each drive roller 16, the plurality of photosensors34 and programmable controllers (FIG. 16) in adjacent conveyor sections.

[0031] As a product unit leaves one active zone 50 a, the product unitbreaks the light beam 42 (FIG. 4) between photosensor 34 and reflector36. This causes a detection signal to be transmitted to the controller54 (FIG. 16) by the photosensor 34. For example, upon receipt of adetection signal from the active zone 50 b, the controller 54 (FIG. 16)generates an activation signal to the drive roller 16 of the active zone50 b as the product unit is entering the zone. Activation of the driveroller 16 initiates movement of the drive roller and all slaved carrierrollers 14. At the same time, a deactivation signal is transmitted tothe drive roller 16 of the active zone 50 a as the product unit isexiting this zone. This process continues as the product unit passesfrom one active zone 50 to another. It is important to note that thedrive roller 16 of an active zone 50 is only activated while a productunit moves through the active zone. When a product unit leaves an activezone 50 and no other product units enter the active zone, the driveroller 16 and slaved carrier rollers 14 are not actuated. This resultsin a conveyor system that uses less power and produces less noise thanpresently existing systems.

[0032] Referring now to FIG. 7, there is shown curved section of themodular power roller conveyor of the present invention. The module ofFIG. 7 comprises a curved conveyor section 60 that change the directionof travel of a product unit by 90°. It is important to note that whilethis particular module illustrates a 90° turn, a turn from anywherebetween 0° and 180° may be constructed. The curved conveyor section 60is supported by legs 62. As before, the curved conveyor section 60comprises a left side rail 64, a right side rail 66, drive rollers 72and carrier rollers (14, 74) mounted between the left side rail 64 andthe right side rail 66. The carrier rollers 74 are connected to thedrive roller 72 by a plurality of o-ring bands 80 such that actuation ofa drive roller will actuate any carrier rollers connected thereto.

[0033] Openings 68 within side rails 64 and 66 facilitate operation ofphotosensors 34 (FIG. 4) and reflectors 36 (FIG. 4). The photosensor andreflector assemblies are mounted in a manner similar to that discussedwith respect to FIG. 3. At each end of the curved conveyor section 60connecting brackets 68 are mounted to the left and right side rails 62and 64 to interconnect the curved conveyor section 60 to other conveyorsections. Each end of the curved conveyor section 60 also includes aelectrical connector mounted in an opening 69 for electrical connectionbetween adjacent modules or a power supply.

[0034] Referring now to FIG. 8, there is illustrated the tapered carrierroller 72 of the curved conveyor section 60. The carrier rollers 14 onthe straight portions of the curved conveyor section 60 are the same asthose discussed with respect to FIG. 3. On the tapered carrier roller72, the carrier roller surface is preferably fabricated from galvanizedsteel tubing overlain with high impact molded copolymer segments. Thesurface forms a continuous taper from a large diameter end 75 to a smalldiameter end 77 to allow efficient movement of a product unit around thecurved section. Spring loaded shafts 76 allow for mounting and removalof the tapered carrier roller 72 within the left and right side frames64 and 66. The tapered carrier rollers 72 are mounted such that thesmall diameter end 77 is placed upon the interior radius of the curvedconveyor section 60. Grooved channels 79 allow for placement of o-ringbands 80 (FIG. 7) between adjacent rollers. Drive rollers 72 have asimilar appearance to the carrier rollers and are preferably twenty-fourvolt electric conveyor rollers as manufactured by the InterrollCorporation.

[0035] Referring to FIG. 9, there is illustrated a top view of thecurved conveyor section 60 of the curved section module. The conveyorsection 60 comprises a number of active zones 61 a-61 d. As a productunit passes between a photosensor 34 and reflector 36 and into an activezone 61 b, the photosensor 34 transmits a detection signal to acontroller 86 (FIG. 16). In response to the detection signal, theprogrammable controller 86 (FIG. 16) generates an activation signal tothe drive roller 72 of the active zone 61 b. The drive roller 72 driveseach of the slaved carrier rollers 74 within the active zone 61 b untilthe product unit passes to the active zone 61 c. The detection signalalso causes the controller 86 (FIG. 16) to generate a deactivationsignal to the drive roller 72 of the active zone 61 a as the productunit is exiting this zone.

[0036] Referring to FIG. 10 and FIG. 11, there is illustrated a top-viewand a side view of a left-hand divert section 81 of a power rollerconveyor. A flexible divert arm 92 is mounted to a side rail 85. Aprogrammable controller 94 (FIG. 16) actuates an air cylinder 83 mountedto the side rail 85 and the extension of the plunger arm within thecylinder 83 extends the flexible divert arm 92 from the side rail 85across the divert section 81. A track 90 in the plane defined by thesurface of the rollers, comprises a narrow groove that serves as a guidefor the flexible divert arm 92. The track extends obliquely from theside rail 85, to the limit of extension of the flexible divert arm 92.When the cylinder 83 is actuated, the divert arm 92 slides along theside rail 85 and along the track 90, into the path of product units 88moving along the conveyor. The bottom edge of the divert arm 92 lieswithin the groove of the track 90 and as product units pass along theconveyor 81 the divert arm 92 is encountered and slides along the divertarm. Positioned at an angle with reference to the divert section 81 is astraight section 98, and product units that encounter the divert arm 92slide along the divert arm into the straight section 98 of power rollerconveyor.

[0037] In a left-hand divert as shown in FIG. 10 the divert arm extendsfrom the side rail 85, but right-hand divert sections are alsoavailable, in which the divert arm 92 extends from the opposite siderail. Also available are dual divert sections in which a divert arm 92extends from each side rail, and a track 90 extends from each side rail,so that product unit may be diverted to the left, to the right, or movestraight ahead according to instructions from the programmablecontroller 94 (FIG. 16).

[0038] An alternative embodiment of the invention includes a right angletransfer arm that moves up from below the surface defined by therollers. The right angle transfer arm is raised by instruction from theprogrammable controller 94 (FIG. 16).

[0039] Referring now to FIG. 12 (a top view), and FIG. 13 (a lateralview), of the divert section 81 in which the divert arm 92 is unactuatedand remains positioned along the side rail 85. A product unit 88 passingalong the conveyor continues in a straight line, as though the sectionwere a straight modular section.

[0040] Referring now to FIG. 14 (a top view), and FIG. 15 (a lateralview), of the divert section 81 the divert arm 92 is actuated andextends from the side rail 85 into the path of the product unit 88moving along the conveyor. The product unit is diverted into the sidepath 98.

[0041] Referring now to FIG. 16, there is shown a schematic of apreferred implementation of the controller. One such controller appearson each conveyor module. A FLASH-RAM 139 (manufacture designationAT29C256) stores ladder logic code as the computer program for themodule. A logic network 137, for example a PSD311 44-pin chip, includesinternal logic to interface with a microprocessor 134. The logic network137 contains a SRAM interconnected to the microprocessor 134; an EPROM;and other logic and switching circuits. The microprocessor 134 controlscircuitry associated with the module. A logic network 138, for example aDS1232, restarts the microprocessor 134 in the event of microprocessorinterruption. Two logic networks 141, for example HCPL-2400 chips, serveas optical isolators for a serial port, protecting the microprocessor134 from voltage surges. A networking interface connects a transorb 136to the microprocessor 134. The transorb 136 clips any voltage above 12volts, sending it to ground. A high-speed one-meg serial port 130 allowsthe microprocessor 134 to communicate with the logic networks 141 of aninterconnected module. A port 140 allows modification and installationof logic code into the FLASH-RAM 139 by a system installer when the siteis initially configured. The inputs of four circuits of the typegenerally shown in FIG. 17 are collectively made available throughterminals 132 to the microprocessor 134. One controller of the typegenerally shown in FIG. 16 is mounted on each module, as describedabove, and measures 8″×6″×2″. Eight digital inputs at terminals 132connect to the input pins of the microprocessor 134 through lightemitting diodes (LED's) 133 connected to the input terminals 132, theseterminals also allow controller diagnostics. Sensor signals at terminals135 from each of several photosensors also serve as inputs to themicroprocessor 134. In the preferred embodiment, the controller operatesfrom a 24 volt AC source, and the interconnected controllers of variousmodules operate in DEVICE NET and SDS. The controllers communicate onDEVICE NET or on SDS application layers.

[0042] Referring now to FIG. 17, there is illustrated a schematic of alogic circuit allowing the controller to alter direction of motion ofitems on the module, and to enable dynamic braking. Four circuitsfunctionally equivalent to the circuit shown in FIG. 17 reside on eachmodule. One input 101 controls dynamic braking; when the value of theinput 101 is zero, dynamic braking is engaged, and the motor driving allrollers associated with the module are stopped. The input 101 is appliedto the input to each of two NOR gates 103 and 104, forcing the outputsof the NOR gates 103 and 104 to zero whenever input 101 has a value ofone. The output of the NOR gates 103 and 104 passes through aresistor-capacitor debouncer 105 or 106 and through an AND gate isolator107 or 108, and finally through a resistor, to a JFET 111 or 112. Thus,when input 101 has a value of one, the output of the NOR gates 103 and104 is zero and the JFETs 111 and 112 close, driving the outputs 123 and124 to ground. This prevents power from reaching the outputs 123 or 124.On the other hand, when input 101 is zero, the outputs are enabled.

[0043] The inverter associated with input 102 ensures that one and onlyone of the two initial NOR gates 103 or 104 will carry a double-zeroinput, allowing an output 103 or 104 of the NOR gates to be zero. Thus,input 102 selects which portion of the circuit to energize. This zerovalue will be passed through the debouncer 105 or 106 and the AND gate107 or 108, keeping the JFET 111 or 112 open; the output 123 or 124 willnot be grounded. The “zero” output from the initial NOR gate 103 or 104is inverted to a “one” as it passes through the final NOR gate 109 or110, providing a non-zero signal that is amplified by the cascadedtransistors 109, 119, 110 and 120 to a rail voltage 117 of 30 volts. Thehigh voltage closes the output JFET 121 or 122 and connects the output123 or 124 to the 30-volt rail voltage 117, powering a motor. Input 102controls the direction of the rollers; the top half of FIG. 17, ifenergized, drive the motor in one direction, and the bottom half drivesthe motor in the other direction, as controlled by an inverter; only oneportion of the circuit will operate at any given time. The circuit asshown in FIG. 17 shows only two inputs, but because four such circuitsappear on any given module, eight inputs are supplied to themicroprocessor (shown in FIG. 16).

[0044] Although preferred and alternative embodiments of the presentinvention have been illustrated in the accompanying Drawings anddescribed in the foregoing Detailed Description, it will be understoodthat the invention is not limited to the embodiments disclosed, but iscapable of numerous rearrangements, modifications and substitutions ofparts and elements without departing from the spirit of the invention.

1. A divert section for a modular conveyor system that includes a seriesof separate conveyor sections connected end-to-end for transporting aproduct unit from one conveyor section to another, wherein the divertsection comprises: a frame; a series of active conveyor zones eachincluding a conveyor mechanism mounted on the frame, each conveyormechanism including a drive roller and a plurality of carrier rollers,the drive rollers and carrier rollers being mounted between side railsof the frame, wherein the active zones define a main path for movementof a product unit and a divert path that branches from the main path; asensor for each zone of each conveyor section, which sensors arepositioned to sense entry of a product unit into the respective activezone and generate a detection signal in response thereto; a divertmechanism, which allows products to travel along the main path whendeactuated and directs product units along the divert path whenactuated; and a programmable controller, including a memory for storingprogram code, a microprocessor for execution of the program code, sensorsignal inputs coupled to the microprocessor for receiving sensor signalsfrom each sensor of the divert section, control circuits coupled to themicroprocessor which permit the microprocessor to individually controlthe conveyor mechanism of each active zone of the divert section,wherein the programmable controller further actuates the divertmechanism to divert selected product units from the main path to thedivert path.
 2. The divert section of claim 1 , further comprising meansfor interconnecting the carrier rollers for rotation in unison with thedrive roller.
 3. The divert section of claim 1 , wherein the divertmechanism includes a pneumatic cylinder, the programmable controlleractuating the pneumatic cylinder to engage the divert mechanism.
 4. Thedivert section of claim 3 , wherein the divert mechanism furtherincludes a divert arm, the divert arm being moved into the main pathupon actuation.
 5. The divert section of claim 1 , further comprisingmeans for interconnecting open ends of the main and divert paths withadjacent conveyor sections.
 6. The divert section of claim 1 , whereinthe programmable controller further comprises a communications interfacewhereby the programmable controller of the divert section can beconnected to and communicate with a programmable controller of anadjacent conveyor section.
 7. The divert section of claim 1 , whereinthe sensors comprise photosensors.